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G8MNY  > TECHNI   02.10.21 11:00l 78 Lines 2573 Bytes #999 (0) @ WW
BID : 48433_GB7CIP
Read: GUEST
Subj: Using a G5RV on 160M
Path: PI8DRE<PI8CDR<LU4ECL<JE7YGF<GB7CIP
Sent: 211002/0851Z @:GB7CIP.#32.GBR.EURO #:48433 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                               (New Aug 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

To use a G5RV or any HF dipole/doublet conveniently to a Marconi T aerial on
topband you will need..

1/ A good earth
2/ A matching coil
3/ Double Pole Relay/switch
4/ Outdoor Box

AERIAL
Tree                                     2nd
Supports                                Support
- -o컴컴컴컴컴컴컴컴켠컴컴컴컴컴컴컴컴훟- -
Insulator            
             Balanced
               Feeder
                     
                     
                     
                     
                 Switched===================Coax to shack
                 Matching  쿐arth
                    Box    퀂takes
                           
SWITCHED MATCHING BOX
This has to house the relay or manual double pole high voltage switch with the
loading coil.

  Balanced
   Feeder 
                  
     o컨컫컴컴컴(((()
RL1_/o   o RL2   L /\
         o\_________
         _         
         /|        
        === C                ___
        /          읕컴컴컴)___Shack
      읕컴좔컴쩡컴컴컴컫컴컴컫   Coax
            Earth   旼컨컴 __
            Stakes  쿝elay \_/
                    읕컫컴      Select
                       읕컴컴좔컴<160M

This circuit is with no HF balun for use on a G5RV or half sized G5RV. If a
dipole is used with then a switched balun & more complex switching is needed.

With the relay released L is shorted out & the feeder is connected to the coax
in the normal way.
With the relay operated the feeder is shorted together & connected to the coax
via the L & a SWR triming cap C. The voltages can be very high (1kV) so a relay
or switch with good contact separation & contacts to spacing is need.

TUNING
Generally a series L (tapped 60 turns on a 3cm dia former) is all that is
needed to get the resonated Z down to near 50/75 with most aerials. But if the
SWR is still to high at resonance the C across the coax (via RL2 contact) of
100-2000pF should bring the Z to an exact match.

BOX
A black plastic box is best. Hermetically sealed boxes really don't seal that
well outdoors. A better approach is to leave a breathing hole in the bottom
(lowest point) so that any water can drain way, but put a fine mesh over it to
stop insects. Paint up & spray all parts with a light oil to resist rusting.

Grease up well, all screws & connectors use outside so any water has no where
to go.


Why Don't U send an interesting bul?

73 de G8MNY @ GB7CIP


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